Building materials, compositions, and methods

ABSTRACT

Building materials include a dampening layer which contains a plaster and a viscoelastic polymer, such as polyvinyl butyral. The dampening layer may also include a barium salt. Methods of making a sound dampening material include providing a plaster mixture. The mixture may include a viscoelastic polymer and/or a barium salt. The plaster mixture is combined with water and/or a viscoelastic polymer dispersion, to form a slurry. The slurry is applied to a surface and set to form a sound dampening layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/722,626, filed on Dec. 20, 2012, which is incorporated byreference in its entirety herein.

BACKGROUND

The present invention relates generally to the field of sound dampeningmaterials, and more particularly to plaster-based materials havingimproved sound dampening properties.

Plaster-based materials are used in a variety of building andconstruction applications where sound dampening properties aredesirable. For example, gypsum panels are used in wall, door, floor,ceiling, roof, and other building applications. In multi-family andcommercial buildings, floor/ceiling assemblies commonly includeplaster-based materials as part of the subfloor structure. For example,gypsum underlayments are typically applied over structural concrete orprecast concrete planks in floor/ceiling assemblies to create a smooth,monolithic floor surface that delivers superior strength, sound control,and fire resistance as compared to Portland cement and other products.

To mitigate impact or airborne related noise from transferring throughsuch structures, acoustical sound mats are commonly laid over concreteor wood subfloors. The mats are a fabric material which creates an airspace between the subfloor and gypsum underlayment. The air space servesto mechanically isolate and decouple impact related vibrations. Thesound mat is typically topped with a pumpable, sanded gypsumunderlayment ¾ to 1 inch thick and screeded to maintain a uniform depthand finish.

However, there are drawbacks to the current system. For example,acoustical sound mats are very expensive per square foot and are timeconsuming and costly to install. Sound mats are also prone to shiftunder heavy loads and/or from hard impacts, which can cause flooring ortiles to crack. For this reason, another costly reinforcement-type mator an even more expensive metal lathing is commonly installed overtopthe sound mats before the gypsum underlayment is poured. Additionally,the acoustical mats create a mechanical air space but do little to abatesound vibrations at high to mid frequencies and must rely predominatelyon the mass and stiffness of the assembly for abatement of thesevibrations.

Accordingly, there is a need for materials having improved sounddampening properties.

SUMMARY

In one aspect, sound dampening materials are provided, including adampening layer which is made up of a plaster and a viscoelasticpolymer, such as polyvinyl butyral. In certain embodiments, thedampening layer also includes a barium salt, such as barium sulfate.

In another aspect, methods of making a sound dampening material areprovided, including providing a plaster mixture, optionally containing aviscoelastic polymer and/or a barium salt, and combining the mixturewith water to form a slurry. In certain embodiments, the water includesa viscoelastic polymer dispersion. The slurry is applied to a surfaceand set to form a sound dampening layer.

In yet another aspect, compositions for sound dampening layers areprovided, including a plaster and a viscoelastic polymer. In certainembodiments, the composition also includes a barium salt.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, which are meant to be exemplary and notlimiting, and wherein like elements are numbered alike:

FIG. 1 is a perspective view of one embodiment of a subfloor assemblyincluding a sound dampening layer.

FIG. 2 is a perspective view of one embodiment of a subfloor assemblyincluding a sound dampening layer.

FIG. 3 is a perspective view of one embodiment of a subfloor assemblyincluding a sound dampening layer.

FIG. 4 is a chart illustrating the internal friction damping of certainembodiments of sound dampening materials.

DETAILED DESCRIPTION

Disclosed herein are materials having improved sound dampeningproperties, and compositions and methods for their manufacture and use.These materials may be used, for example, in building and constructionapplications where impact and/or airborne noise abatement is desirable,such as in doors, roofs, walls, floors, and ceilings. In certainembodiments, the sound dampening materials described herein may be usedin gypsum underlayment systems, for example in floor/ceiling assembliesin multifamily or commercial buildings.

Such materials may have sound attenuation properties that meet regionalor national building codes. For example, floor/ceiling assemblies mayhave a minimum Impact Insulation Class (IIC) rating of 50, as measuredaccording to ASTM E989, and/or a minimum Impact Insulation Class Fieldrating of 45, as measured according to ASTM 1007.

In certain embodiments, a sound dampening material has a dampening layerincluding a plaster and a viscoelastic polymer. For example, the plastermay include alpha hemihydrate gypsum, beta hemihydrate gypsum, finegrind molding plaster, fly ash type C, Type I Portland cement, Type IIPortland cement, dispersant, retarder, defoamer, boric acid,landplaster, or any combination thereof. In one embodiment, the plasteris a sanded gypsum. For example, the sand may include washed sands,masonry sands, plaster sands, and any combination thereof

The viscoelastic polymer may be selected from the group consisting ofpolyvinyl butyral, acrylics, polyurethanes, vinyl ethers, ethylene vinylacetates, styrene block copolymers, polyolefin copolymers, butyl rubber,natural rubber, silicones, and nitriles. In one embodiment, theviscoelastic polymer is polyvinyl butyral (PVB). For example, thedampening layer may include the viscoelastic polymer in an amount fromabout 0.5 wt. % to about 50 wt. %. In certain embodiments, the dampeninglayer includes the viscoelastic polymer in an amount from about 5 wt. %to about 15 wt. %.

Without being bound by a particular theory, it is believed that theviscoelastic polymer within the dampening layer undergoes plasticdeformation under impact and under static loads when the layer isstressed, for example from people walking or dropping things on thefloor. It is also believed that the viscoelastic polymer within thedampening layer advantageously has the ability to absorb vibrationalenergy as well as dissipate vibrational energy as frictional heat,thereby reducing the amount of energy transferred though the materialand the amount of noise transferred to adjacent structures. Thus, thematerials described herein may provide impact and airborne noiseabatement, as opposed to traditional fabric sound mats, which generallyprovide minimal impact noise abatement.

In certain embodiments, the dampening layer also includes a barium salt.For example, the barium salt may be selected from the group consistingof barium sulfate, barium oxide, barium chloride, barium fluoride,barium sulfide, barium carbonate, barium peroxide, barium hydride, andcombinations thereof. In one embodiment, the dampening layer includes aplaster, a viscoelastic polymer, and barium sulfate. In one embodiment,the dampening layer includes a viscoelastic polymer and a barium salt.For example, the dampening layer may include a barium salt in an amountfrom about 1 wt. % to about 70 wt. %., or in an amount from about 35 wt.% to about 55 wt. %.

In certain embodiments, the dampening layer also includes a high atomicweight material, a high molecular density material, or a combinationthereof. For example, the high atomic weight material or the highmolecular density material may be selected from the group consisting ofbarium sulfate, calcium silicate, zinc oxide, lead, zirconium dioxide,carbonyl iron powders, aluminum powder, iron powder, stainless steelpowder, copper powder, bismuth powder, tungsten powder, lead powder,bismuth oxide powder, niobium powder, tantalum powder, molybdenumpowder, Borated HDPE, fly ash class C, and any combination thereof

Without being bound by a particular theory, it is believe that thebarium salt and/or high atomic weight/molecular density material addsmass to the layer, which is effective to initially resist vibration, butalso acts synergistically with the viscoelastic polymer to increase thedampening capacity.

For example, the dampening layers described herein may be used as sounddampening materials in floor/ceiling underlayments. In certainembodiments, a method of dampening sound through a structure includesdisposing a dampening layer as described herein on a surface of orwithin the structure. For example, the dampening layer may include aplaster and a viscoelastic polymer. The structure may be a wall, door,floor, ceiling, roof, floor/ceiling assembly, or other building materialfor which sound dampening properties are desirable.

The dampening layers described herein are advantageously pumpable innature and therefore may be easily applied to a subfloor (e.g., aconcrete or wood subfloor) in the field. For example, as shown in FIG.1, a subfloor assembly 100 includes a subfloor 120 that is supported bya support beam 130 that is adjacent a plaster board 140 (e.g., a gypsumboard). Dampening layer 110 may be applied on the subfloor 120 andscreeded to achieve a uniform thickness and finish. The dampening layermay be utilized in place of a standard underlayment or may be used inconjunction with a standard underlayment. For example, as shown in FIG.3, dampening layer 310 is applied to subfloor 320 and underlayment layer312 is applied to the surface of the dampening layer 310 opposite thesubfloor 320.

In certain embodiments, the dampening layer has a thickness of at least0.03 inch. For example, the dampening layer may have a thickness ofabout 0.25 inch to about 1 inch. In one embodiment, the dampening layeris only as thick as is necessary to achieve a continuous layer. Anyadditional underlayment layer (e.g., a sanded gypsum underlayment) mayhave a thickness of at least 0.03 inch. For example, the underlaymentlayer may have a thickness of about 0.5 inch to about 1.0 inch.

The sound dampening material may have an internal friction of at least0.004. For example, the sound dampening material may have an internalfriction of about 0.005 to about 0.020. The internal friction of thesound dampening material is higher than that of traditional sounddampening materials, which advantageously allows the sound dampeningmaterial to dampen high and medium frequencies.

The sound dampening material may have an Impact Insulation Class (IIC)rating of 45 or greater. For example, the sound dampening material mayhave an IIC rating from 35 to 55.

Compositions for making sound dampening layers may include a plaster anda viscoelastic polymer, optionally with a barium salt, a high atomicweight, or a high molecular density material, as described above.

Methods for making the sound dampening materials described hereingenerally may include providing a plaster mixture, combining the mixturewith water to form a slurry, applying the slurry to a surface, andsetting the slurry to form a dampening layer. The plaster mixture mayinclude alpha hemihydrate gypsum, beta hemihydrate gypsum, fine grindmolding plaster, fly ash type C, Type I Portland cement, Type IIPortland cement, dispersant, retarder, defoamer, boric acid,landplaster, or any combination thereof. For example, the water may becombined in an amount of about 30 wt. % to about 70 wt. %. For example,water may be added in an amount effective to bring the plaster mixtureto a pumpable consistency.

In certain embodiments, the plaster mixture includes a viscoelasticpolymer, such as PVB. For example, the viscoelastic polymer may bepresent in the mixture in an amount from about 0.5 wt. % to about 50 wt.%, or from about 5 wt. % to about 15 wt. %. In certain embodiments, PVBis in a particulate form, for example having an average particle size ofabout 100 nanometer to about 1000 microns. In other embodiments, theplaster mixture is combined with a viscoelastic polymer dispersion inwater to form the slurry. For example, the dispersion may includepolyvinyl butyral in an amount from about 1 wt. % to about 75 wt. %.

In certain embodiments, the plaster mixture includes a barium salt, ahigh atomic weight material, and/or a high molecular density material.For example, the high atomic weight material or the high moleculardensity material may be selected from the group consisting of bariumsulfate, calcium silicate, zinc oxide, lead, zirconium dioxide, carbonyliron powders, aluminum powder, iron powder, stainless steel powder,copper powder, bismuth powder, tungsten powder, lead powder, bismuthoxide powder, niobium powder, tantalum powder, molybdenum powder,Borated HDPE, fly ash class C, and any combination thereof. For example,the barium salt may be selected from the group consisting of bariumsulfate, barium oxide, barium chloride, barium fluoride, barium sulfide,barium carbonate, barium peroxide, barium hydride, and combinationsthereof. In certain embodiments, barium sulfate is added to the mixturein particulate form having an average particle size of 325 micron.

The slurry may be applied to a surface, for example a subfloor. Forexample, the slurry may be pumped onto the surface. The slurry may beallowed to set and form a dampening layer, for example by properlyventilating the layer for at least five to seven days.

In certain embodiments, the dampening layer has a thickness of at least0.03 inch. For example, the dampening layer may have a thickness ofabout 0.25 inch to about 1 inch. In one embodiment, the dampening layeris only as thick as is necessary to achieve a continuous layer.

The sound dampening layer made by these methods may have an internalfriction of at least 0.004. For example, the sound dampening layer mayhave an internal friction of about 0.005 to about 0.020.

As shown in FIG. 1, the sound dampening layer 110 may act as the soleunderlayment of a subfloor assembly 100. The sound dampening layer 110may be pumped onto the subfloor 120 and allowed to set. In suchembodiments, the dampening layer may have a thickness of about 0.75 inchto about 1 inch. Flooring, such as ceramic tile 160, may be applied tothe set surface of the dampening layer 110.

As shown in FIG. 2, the sound dampening layer 210 may be applied to thesurface of a sound isolation mat 250 to increase the sound dampeningattributes of subfloor assembly 200. For example, the sound isolationmat may include commercially available board or roll-type soundunderlayment mats, such as woven, non-woven, felt, rubber, cork,polymeric, or other mats.

As shown in FIG. 3, the dampening layer 310 may applied to subfloor 320and an underlayment layer 312 may be applied to the surface of thedampening layer 310 opposite the subfloor 320. In such embodiments, thedampening layer may have a thickness of about 0.25 inch to about 0.5inch. The additional underlayment layer (e.g., a pumpable sanded gypsumunderlayment) may have a thickness of at least 0.03 inch. For example,the underlayment layer may have a thickness of about 0.5 inch to about1.0 inch. After application to the dampening layer, a plasterunderlayment slurry may be allowed to set to form a plasterunderlayment.

The sound dampening material may cause the subfloor assembly to have anImpact Insulation Class (IIC) rating of 45 or greater. For example, thesubfloor assembly may have an IIC rating from 35 to 55.

EXAMPLES

Embodiments of the dampening materials disclosed herein weremanufactured and tested for sound dampening properties. The results areshown in FIGS. 4, 5, and 6.

Tests were conducting using a Buzzsonic 5.9 instrument designed to testsolid materials by the Impulse Excitation Technique (IET). Specifically,the device measures and analyzes vibrational responses of impulseexcited solids, such as ceramics, metals, composites, polymers, buildingproducts, paper board, etc.

Sound dampening material 4″ by 4″ test samples were prepared asdescribed below. The samples were tested as a single or layeredconstruction and placed across a span of thin nylon threads, whichreduce external damping. The samples were then tapped lightly with asmall hammer, thereby generating a standing wave in the solid. Theresulting sound was captured with a microphone directly underneath thesample and attached to a computer that analyzes the sound using a FastFourier Transform algorithm. The waveform and power/frequency spectrumof the sound were determined, from which the damping properties andresonant frequencies were calculated. The peak amplitude of vibrationsof an impulse-excited solid follows an exponential decay. The dampingratio, which determines system damping capacity, and the internalfriction of the material Q̂A-1 (obtained from the damping ratio) wereused in evaluating materials. The internal friction calculated from thewaveform exponential decay curve was used as the primary means ofdifferentiating between samples.

FIG. 4 shows the results obtained from single ½″ sound dampening layerswith a ½″ standard underlayment layer over the acoustical mat product.Results are shown as ANOVA boxplots with mean connecting lines. For eachcondition, the box portion of the box plot is divided into quartilesections. The box shows 50% of the response for that condition with theouter two quartiles as whiskers and showing the remaining uppermost andlowermost quartiles of responses.

The ACOUSTIMAT products range includes the combined results ofACOUSTIMAT II and ACOUSTIMAT III products (commercially available fromMaxxon Corporation, located in Hamel, Minn.), which include a non-wovenfabric mat and a standard gypsum underlayment, such as DURA-CAP(commercially available from Maxxon Corporation). The ACOUSTIMATproducts range represents the current sound dampening characteristics ofdampening materials incorporating sound mats. A DURA-CAP panel was alsotested as a comparative control. DURA-CAP plaster was used as theplaster base for the dampening layer samples.

FIG. 4 shows the damping ability (Q̂-1) of the tested samples. A higherQ̂-1 indicates a higher damping ability. The first dampening layer sampleincluded DURA-CAP gypsum plaster and 5 wt. % PVB added as a 400 micronpowder (commercially available from Shark Solutions LTD, located inDenmark) and clearly outperformed the standard DURA-CAP underlayment andfell within the lower performance end of the sound mat comparativesamples. As more PVB powder was added up to 10 wt. %, the amount ofdampening went up incrementally.

Barium sulfate was added to the plaster and PVB formulations, and thesesamples outperformed the samples having only PVB, especially at a ratioof 40 wt. % barium sulfate to 10 wt. % PVB. In the final sample, adispersion of PVB (commercially available from Shark Solutions LTD) wasadded to the make-up water, which was then combined with the bariumsulfate and plaster. This sample performed the best of all the samples.Without being bound by a particular theory, it is believed that thesuperior performance of the dispersion is due to the particle size andbetter distribution of the PVB in the ultimate matrix. However, PVBdispersants may interfere with the water demand and ultimately finishedstrength properties.

While the disclosure has been described with reference to a number ofembodiments, it will be understood by those skilled in the art that theinvention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions, or equivalent arrangements not describedherein, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A sound dampening composition, comprising aplaster, polyvinyl butyral, and a material selected from the groupconsisting of barium salts, high atomic weight materials, high moleculardensity materials, and combinations thereof
 2. The composition of claim1, wherein the polyvinyl butyral is present in the composition in anamount from about 0.5 weight percent to about 50 weight percent.
 3. Thecomposition of claim 1, wherein the polyvinyl butyral is present in thecomposition in an amount from about 5 weight percent to about 15 weightpercent.
 4. The composition of claim 1, wherein the high atomic weightmaterial or the high molecular density material is selected from thegroup consisting of barium sulfate, calcium silicate, zinc oxide, lead,zirconium dioxide, carbonyl iron powders, aluminum powder, iron powder,stainless steel powder, copper powder, bismuth powder, tungsten powder,lead powder, bismuth oxide powder, niobium powder, tantalum powder,molybdenum powder, Borated HDPE, fly ash class C, and combinationsthereof
 5. The composition of claim 1, wherein the material is bariumsalt selected from the group consisting of barium sulfate, barium oxide,barium chloride, barium fluoride, barium sulfide, barium carbonate,barium peroxide, barium hydride, and combinations thereof
 6. Thecomposition of claim 1, wherein the material is barium salt and thebarium salt is present in the composition in an amount from about 1weight percent to about 70 weight percent.
 7. The composition of claim1, wherein the material is barium salt and the barium salt is present inthe composition in an amount from about 35 weight percent to about 55weight percent.
 8. A sound dampening composition, comprising a plaster,a barium salt, and a viscoelastic polymer, wherein the viscoelasticpolymer is present in the composition in an amount from about 0.5 weightpercent to about 50 weight percent.
 9. The composition of claim 8,wherein the viscoelastic polymer is present in the composition in anamount from about 5 weight percent to about 15 weight percent.
 10. Thecomposition of claim 8, wherein the barium salt is selected from thegroup consisting of barium sulfate, barium oxide, barium chloride,barium fluoride, barium sulfide, barium carbonate, barium peroxide,barium hydride, and combinations thereof
 11. The composition of claim 8,wherein the barium salt is present in the composition in an amount fromabout 1 weight percent to about 70 weight percent.
 12. The compositionof claim 8, wherein the barium salt is present in the composition in anamount from about 35 weight percent to about 55 weight percent.
 13. Thecomposition of claim 8, wherein the viscoelastic polymer is selectedfrom the group consisting of polyvinyl butyral, acrylics, polyurethanes,vinyl ethers, ethylene vinyl acetates, styrene block copolymers,polyolefin copolymers, butyl rubber, natural rubber, silicones,nitriles, and combinations thereof
 14. A method of making a sounddampening composition, comprising: combining water, a plaster, polyvinylbutyral, and a material selected from the group consisting of bariumsalts, high atomic weight materials, high molecular density materials,and combinations thereof, to form a slurry; and setting the slurry toform a composition.
 15. The method of claim 14, wherein the high atomicweight material or the high molecular density material is selected fromthe group consisting of barium sulfate, calcium silicate, zinc oxide,lead, zirconium dioxide, carbonyl iron powders, aluminum powder, ironpowder, stainless steel powder, copper powder, bismuth powder, tungstenpowder, lead powder, bismuth oxide powder, niobium powder, tantalumpowder, molybdenum powder, Borated HDPE, fly ash class C, and anycombination thereof.
 16. The method of claim 14, wherein the material isbarium salt selected from the group consisting of barium sulfate, bariumoxide, barium chloride, barium fluoride, barium sulfide, bariumcarbonate, barium peroxide, barium hydride, and combinations thereof 17.A method of making a sound dampening composition, comprising: combiningwater, a plaster, a barium salt, and a viscoelastic polymer, to form aslurry; and setting the slurry to form a composition, wherein theviscoelastic polymer is present in the composition in an amount fromabout 0.5 weight percent to about 50 weight percent.
 18. The method ofclaim 17, wherein the viscoelastic polymer is present in the compositionin an amount from about 5 weight percent to about 15 weight percent. 19.The method of claim 17, wherein the barium salt is selected from thegroup consisting of barium sulfate, barium oxide, barium chloride,barium fluoride, barium sulfide, barium carbonate, barium peroxide,barium hydride, and combinations thereof.
 20. The method of claim 17,wherein the viscoelastic polymer is selected from the group consistingof polyvinyl butyral, acrylics, polyurethanes, vinyl ethers, ethylenevinyl acetates, styrene block copolymers, polyolefin copolymers, butylrubber, natural rubber, silicones, nitriles, and combinations thereof